1. Field of the Invention
This invention relates to AC reactance sensor circuitry and more particularly to capacitance transducers for measuring pressure.
2. Prior Art
In the prior art, various AC reactance measuring schemes are shown. While many such techniques have been successful, a problem of prior art schemes has been that typically the amplitude of the (peak to peak) voltage applied to the sensor circuitry has been the controlled parameter for such circuitry and change in the voltage results in reduced stability of the output signal.
One further significant disadvantage has been the requirement of driving a transformer to provide such peak to peak voltage to a varying reactive load. As known to those skilled in the art, a transformer, though faithful once operable, is more difficult to reliably acquire than resistors, capacitors, or solid state components. Elimination of the transformer results in a reduction of size and power required. A further problem is that such transformers do not lend themselves to use with hybrid circuitry. Such hybrid circuitry with an interactive or capacitive sensor is desirable. Elimination of such transformers results in a functionally improved, lower cost circuit.